The ability to detect and identify radiation such as gamma rays is a very useful tool for a variety of applications. The applications range from medical imaging systems to anti-terrorism security monitors. For example, the gamma rays emitted by a concealed “dirty bomb” will give away the bomb's location if properly detected and identified. Gamma ray detection can also be used to map hot spots following a nuclear accident or to monitor for leakage of radioactive waste.
One type of gamma ray detection system that has been proposed uses a block of fiber-optic scintillators. Incident gamma rays scatter within the scintillator block depositing energy at various locations. Some of this energy is converted to scintillation light by the fiber-optic scintillators. By detecting the locations and intensities of this scintillation light generated within the scintillator block, the energy and direction of the incident gamma rays can be determined. U.S. application Ser. No. 10/866,760, entitled “Gamma Vector Camera” and filed on Jun. 15, 2004, describes a method and system for making such determination and is hereby incorporated herein by reference.
To capture the scintillation light, charge-coupled devices (CCD) may be used to record the locations and intensities of the scintillation light generated by the scintillator block. CCDs offer a solution that is generally cost effective and readily available for implementation. However, the scintillation light generated within a scintillator block is relatively weak. This weakness, together with the average noise levels of CCDs, can prevent the accurate recording of intensities and locations of the scintillation light.
Amplification of the scintillation light before it reaches the CCD offers one solution to overcoming noise within a CCD. For example, an image intensifier may be used to amplify the scintillation light above the average noise level of the CCD. However, image intensifiers introduce noise, such as thermal noise, to the system.
Accordingly, a need exists for a system capable of amplifying scintillation light to a level high enough to overcome CCD noise levels and capable of minimizing the effects of noise introduced to the system by the light amplifier.